Gap between custom scrollbar and content

[JElliottLewis]

Hi there, new Elementor and web builder here. I'm trying to use a custom scrollbar to set a content window height to get my design right. But no matter what selector I pin my scrollbar to I get this gap. I don't mind making the scrollbar double width as that is closer to what I was looking for design wise anyway. But I can't for the life of me figure out what's going on.

Thanks so much, any help is appreciated